I'm finding it difficult to reconcile the rifle locking back on empty (indicating sufficient gas drive) and needing the gas port opened up. Your problem may be magazine or ammo related.
Last edited by georgeib; 04-07-21 at 05:14.
Ahh. Got it now.
Still inclined to think that the gas port size is sufficient. Mine has a 0.080 on a mid-length 18" barrel, and I had to use an adjustable gas block almost completely closed to tame the over gassing. Even with cheaper brass cased ammo. Is there someone you can borrow a BCG from to test?
Interesting everybody thinks 075 intermediate 308 is perfectly fine.
It's certainly possible the NiB BCG is the issue.
The gas key diameter and bolt tail seal diameter should be checked.
Also, the BCG could be swapped for a known good unit.
Black River Tactical
BRT OPTIMUM Hammer Forged Chrome Lined Barrels - 11.5", 12.5", 14.5", 16"
BRT EZTUNE Preset Gas Tubes - PISTOL, CAR, MID, RIFLE
BRT Bolt Carrier Groups M4A1, M16 CHROME
BRT Covert Comps 5.56, 6X, 7.62
Black River Tactical
BRT OPTIMUM Hammer Forged Chrome Lined Barrels - 11.5", 12.5", 14.5", 16"
BRT EZTUNE Preset Gas Tubes - PISTOL, CAR, MID, RIFLE
BRT Bolt Carrier Groups M4A1, M16 CHROME
BRT Covert Comps 5.56, 6X, 7.62
Double tap
Black River Tactical
BRT OPTIMUM Hammer Forged Chrome Lined Barrels - 11.5", 12.5", 14.5", 16"
BRT EZTUNE Preset Gas Tubes - PISTOL, CAR, MID, RIFLE
BRT Bolt Carrier Groups M4A1, M16 CHROME
BRT Covert Comps 5.56, 6X, 7.62
Got back to the range tonight after making some changes to my carbine’s gas and buffer system. I’m relieved to report it runs as it should and reliably locks the bolt back on an empty mag. To fix it, I enlarged the barrel gas port with a #44 drill (.086) and swapped the Aero 3.8 ounce buffer and spring for one of Slash’s 5.5 ounce SS buffers and proprietary springs. The gurus over at the 308 AR forum were a tremendous help.
Last edited by Black_Sheep; 04-15-21 at 19:56.
I had a few issues with my 308 build when I first put it together. I could lock the bolt back with the charging handle, but it would not reliably lock back while shooting. It all came back to an incorrect buffer and spring in the buffer tube. That’s where I would look first.
Sent from my iPhone using Tapatalk
Bookmarks